Landing gear deployment

ABSTRACT

An aircraft controller configured to determine a period and/or distance over which deployment of a landing gear can be initiated for landing including a determined first portion during which landing gear deployment can be safely initiated and a determined second portion, closer to aircraft landing than the first portion, during which the landing gear deployment can be safely initiated in an efficient landing mode; issue a first pilot feedback when the first portion is entered by the aircraft; issue a second pilot feedback when the second portion of the determined; and initiate landing gear deployment when the aircraft is in the determined period and/or distance in response to receiving a deployment signal from the pilot.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/776,896, filed Jan. 30, 2020, and claims priority to United KingdomPatent Application GB 1901381.2, filed Jan. 31, 2019, the entirety ofeach of these applications is incorporated by reference.

TECHNICAL FIELD

The present invention relates to systems and methods for extending anaircraft landing gear.

BACKGROUND

There is a general desire for aircraft flight to be more efficient. Byway of example, efficiency can be improved by reducing flight times andreducing fuel consumption. One aspect of flight in which efficiency canbe improved is aircraft landing procedures, which typically involvedecreasing aircraft altitude and speed from cruise conditions anddeploying the landing gear(s) of the aircraft on approach to an aircraftlanding site such as an airport.

Deploying a landing gear typically involves moving a landing gear from aretracted position to an extended position. In the retracted position,the landing gear is stowed in a landing gear bay within the fuselage ofthe aircraft. In the extended position, the landing gear is movedoutward of the fuselage into a position for supporting the aircraft uponlanding. Deploying a landing gear may also involve moving one of morelanding gear doors from a closed position to an open position, and thenback to the closed position once the landing gear has reached theextended position.

SUMMARY

A first aspect of the present invention provides an aircraft controllerconfigured to: receive an aircraft landing gear deployment signal,receive an aircraft position signal indicative of a distance of theaircraft from an aircraft landing site, receive one or more flightsignals indicating respective one or more dynamic conditions orparameters relating to the flight of the aircraft, determine, based atleast on the received one or more flight signals, a first aircraftposition, relative to the aircraft landing site, at which the landinggear should be deployed and, based on the deployment signal and theaircraft position signal, trigger landing gear deployment (a) when theaircraft reaches the first aircraft position, in the event that thedeployment signal is received before the aircraft reaches the firstaircraft position, or (b) immediately, in the event that the deploymentsignal is received when the aircraft has passed the first aircraftposition.

Optionally, the aircraft controller is configured to dynamicallydetermine the first aircraft position based on changes to the receivedone or more flight signals over time. Optionally, the one or more flightsignals indicate dynamic parameters of the aircraft. Optionally, the oneor more flight signals indicate atmospheric conditions at or near theaircraft landing site.

Optionally, the aircraft controller is configured to determine a secondaircraft position, relative to the aircraft landing site, whichindicates the closest aircraft position to the aircraft landing site atwhich the landing gear can be deployed for a safe landing, and, in theevent that the aircraft reaches the second position before thedeployment signal has been received, automatically trigger landing geardeployment.

Optionally, the one or more flight signals comprises an aircraft speedsignal, and the controller is configured to determine the secondaircraft position based at least on aircraft speed and a landing geardeployment time.

Optionally, the aircraft controller is configured, in the event that theaircraft reaches the second position before the deployment signal hasbeen received, to trigger accelerated landing gear deployment.

Optionally, the aircraft controller is configured to receive a landinggear status signal indicative of a status of the landing gear in thedeployed position and trigger an automatic go-around if the landing gearstatus signal indicates a fault in the deployment of the landing gear.

Optionally, the aircraft controller is configured, in the event that thedeployment signal is received before the aircraft reaches the firstaircraft position, to trigger a pre-landing landing gear system checkbefore triggering landing gear deployment.

Optionally, the aircraft controller comprises a memory configured tostore aircraft landing site information, wherein the controller isconfigured to determine the first aircraft position based on theaircraft landing site information.

Optionally, the aircraft controller is configured, in the event that theaircraft reaches the first aircraft position before the deploymentsignal is received, to trigger an aircraft system to issue a deploymentwarning to the aircraft pilot.

Optionally, the aircraft controller is operable in a first mode,according to the first aspect of the invention, and in a second mode, inwhich, in the event that the deployment signal is received before theaircraft reaches the first aircraft position, the controller triggerslanding gear deployment immediately upon receipt of the landing geardeployment signal. Optionally, the mode of the controller is selectableby the aircraft pilot.

A second aspect of the present invention provides an aircraft controllerto: determine a time period and/or distance range over which deploymentof a landing gear can be initiated for aircraft landing, wherein thedetermining is based on the prevailing conditions during the aircraftlanding and information related to the aircraft and the aircraft landingsite, and wherein the determined time period and/or distance rangecomprises a determined first portion, during which it is safe toinitiate landing gear deployment, and a determined second portion,closer to aircraft landing than the first portion, during which it issafe to initiate landing gear deployment in an efficient landing mode,issue a first pilot feedback when the first portion of the determinedtime period and/or distance range is entered by the aircraft, the firstpilot feedback indicating that it is safe to deploy the landing gear,issue a second pilot feedback when the second portion of the determinedtime period and/or distance range is entered by the aircraft, the secondpilot feedback indicating that the landing gear can be lowered in theefficient landing mode, and initiate landing gear deployment when theaircraft is in the determined time period and/or distance range, inresponse to receiving a deployment signal from the pilot.

Optionally, the aircraft controller is configured to issue a pilotwarning if the aircraft passes a threshold time or threshold distancebefore the controller receives the deployment signal from the pilot,wherein the threshold time or distance is within the determined timeperiod and/or distance range and closer to aircraft landing than thesecond portion, and wherein the pilot warning indicates that landinggear deployment is required urgently.

Optionally, the aircraft controller is configured to issue a third pilotfeedback in the event that the aircraft exits the determined time periodand/or distance range before the controller receives the deploymentsignal from the pilot, the third pilot feedback indicating thatinitiating landing gear deployment has been performed automatically bythe controller.

Optionally, the aircraft controller is configured to delay initiation oflanding gear deployment until the aircraft enters the determined timeperiod and/or distance range, in the event that the deployment signal isreceived before the aircraft enters the determined time period ordistance range.

A third aspect of the present invention provides an aircraft landinggear system comprising: an aircraft landing gear movable between aretracted position and an extended position, an aircraft landing gearextension and retraction system configured to move the landing gearbetween the retracted position and the extended position, and anaircraft controller according to the first or second aspect of thepresent invention, wherein the system is configured such that thetrigger for landing gear deployment causes the landing gear extensionand retraction system to deploy the landing gear.

A fourth aspect of the present invention provides an aircraft comprisingan aircraft controller according to the first or second aspect of thepresent invention or an aircraft landing gear system according to thethird aspect of the present invention.

A fifth aspect of the present invention provides a method for deployingan aircraft landing gear. The method comprises: receiving an aircraftlanding gear deployment signal, receiving an aircraft position signalindicative of a distance of the aircraft from an aircraft landing site,receiving one or more flight signals indicating one or more dynamicconditions or parameters relating to the flight of the aircraft,determining, based at least on the one or more flight signals, a firstaircraft position, relative to the aircraft landing site, at which thelanding gear deployment should commence, and deploying the landing gear(a) when the aircraft reaches the first aircraft position, in the eventthat the deployment signal is received before the aircraft reaches thefirst aircraft position, or (b) immediately, in the event that thedeployment signal is received when the aircraft has passed the firstaircraft position.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of a landing gear system according to anembodiment of the present invention;

FIG. 2 is a diagram depicting an example aircraft flight path onapproach to an aircraft landing site;

FIG. 3 is a flow diagram depicting a method according to an embodimentof the present invention;

FIG. 4 is a flow diagram depicting a method according to an embodimentof the present invention;

FIG. 5 is a flow diagram depicting a method according to an embodimentof the present invention;

FIG. 6 is a flow diagram depicting a method according to an embodimentof the present invention;

FIG. 7 is a flow diagram depicting a method according to an embodimentof the present invention;

FIG. 8 is a schematic front view of an aircraft according to anembodiment of the present invention.

DETAILED DESCRIPTION

As airports around the world look to expand, there is a desire toincrease air traffic without significantly increasing the environmentalimpact of the airport on the surrounding area and without reducingsafety.

It has been found that there are benefits to delaying deployment of alanding gear during an aircraft landing procedure compared to when alanding gear is typically deployed, so that the landing gear is in adeployed state for a shorter period before aircraft landing. Suchbenefits may include: increasing safety by decreasing the risk of damageto the landing gear from debris, improved fuel efficiency due todecreased aircraft drag until the landing gear is deployed, reducing thenoise signature of the aircraft until the landing gear is deployed(which may be of particular importance for airports close to urban areasbecause flying with a deployed landing gear can increase the aircraftnoise signature during an approach phase by 3-5 dB) and smoother landingdue to decreased turbulence during the approach.

At present, landing gear deployment is typically initiated in responseto a trigger by an aircraft pilot and the landing gear remains in adeployed state as the aircraft approaches an aircraft landing site suchas an airport runway. A commercial aircraft may typically comprise anose landing gear and two main landing gears, although any other numberof landing gears may be employed.

Embodiments of the invention permit landing gear deployment when anaircraft is closer to the aircraft landing site compared to a typicalaircraft landing procedure. The disclosed embodiments may permitdetermination an optimum point or range for landing gear deployment,which may be related to specific details of the particular aircraftlanding procedure i.e., related, for example, to the specific airport,the particular aircraft or aircraft type and the specific flightconditions. The disclosed embodiments may help to ensure that landinggear deployment occurs before it is no longer safe to perform landinggear deployment for a successful landing.

FIG. 1 is a schematic view of an aircraft landing gear system 10according to an embodiment of the invention. The system 10 comprises anaircraft landing gear 20 movable between a retracted position and anextended position. The landing gear 20 may be a main landing gear or anose landing gear. The system 10 comprises a landing gear extension andretraction system 30 configured to move the landing gear 20 between theretracted position and the extended position. In some embodiments, thesystem 10 may also comprise one or more landing gear doors (not shown)movable between a closed position and an open position, and the landinggear extension and retraction system 30 may be configured to move thelanding gear doors between the closed position and the open position todeploy the landing gear 20.

The system 10 comprises a controller 100. The system 10 is configuredsuch that a trigger issued by the controller 100 to initiate deploymentof the landing gear 20 causes the landing gear extension and retractionsystem 30 to deploy the landing gear 20.

An aircraft may comprise a plurality of aircraft landing gear systems10. Such a plurality of systems 10 may comprise a common controller 100or each landing gear system 10 may comprise its own controller 100.

In some embodiments, the controller 100 comprises a memory 110. Thememory 110 may be configured to store information received from otheraircraft systems, or information relating to the aircraft landing sitewhich the aircraft is approaching. In some embodiments, the controller100 comprises a processor (not shown), which may be configured to accessand process information stored in the memory 110. In other embodiments,the controller 100 may not comprise a memory 110 and may instead usereceived signals without storing the information.

Operation of a controller 100 according to the invention will now bedescribed with reference to FIG. 2 .

FIG. 2 is a schematic diagram of an aircraft flight path 50 during anaircraft landing procedure. The aircraft altitude is plotted against thetime/distance to the aircraft landing site 40. In some embodiments, acontroller 100 according to the invention is configured to determine atime period and/or distance range 200 over which deployment of a landinggear 20 can be initiated for aircraft landing. The determined timeperiod 200 may span a number of minutes based on a time-to-landing. Thedetermined time period 200 may end at a latest time-to-landing 210 atwhich landing gear deployment can be safely initiated. The determineddistance range 200 may be a span of a number of kilometres from theaircraft landing site 40. The determined distance range 200 may end at aclosest distance 210 to the aircraft landing site 40 at which thelanding gear deployment can be safely initiated.

The determining of the time period and/or distance range 200 is based onthe prevailing conditions during the aircraft landing and informationrelated to the aircraft and the aircraft landing site 40. For example,the speed of the aircraft may determine the start and end points 208,210 of the time period and/or the distance range 200. Informationrelated to the aircraft may comprise, for example, the type of aircraft,the condition of the aircraft brakes and/or tyres, the weight of theaircraft, aircraft altitude and flap position. Information related tothe aircraft landing site 40 may comprise, for example, the length ofthe runway, the distance along the runway at which the aircraft is toturn off, the topography of the runway and the topography below theflight path 50 on approach to the aircraft landing site 40. Informationrelated to the prevailing conditions during the aircraft landing maycomprise, for example, the temperature and weather conditions at theaircraft landing site 40 (for example, a wet or icy runway may mean alonger stopping distance and therefore earlier deployment so that theaircraft can land closer to the start of the runway), the temperatureand environmental conditions surrounding the aircraft on approach, thetime of day of the landing (noise restrictions may be variablethroughout the day), wind direction and the direction of approach to theaircraft landing site 40.

The determined time period and/or distance range 200 may comprise adetermined first portion 202, during which it is safe to initiatelanding gear deployment, and a determined second portion 204, closer toaircraft landing than the first portion 202, during which it is safe toinitiate landing gear deployment in an efficient landing mode. Deployingthe landing gear 20 in an efficient landing mode may, for example, helpto reduce overall aircraft drag during an aircraft landing procedure, ormay reduce the overall noise signature of the aircraft during theaircraft landing procedure until the landing gear 20 is deployed.

The start point 208 of the determined time period and/or distance rangemay be determined based on, for example, a threshold aircraft altitudeor a threshold time-to-landing. The end point 210 of the determined timeperiod and/or the distance range may be based on a time required tosafely deploy the landing gear 20 from initiation of landing geardeployment to ensure that the landing gear 20 is deployed by a thresholdtime and/or distance 215 before aircraft landing.

The controller 100 is configured to issue a first pilot feedback whenthe first portion 202 of the determined time period and/or distancerange 200 is entered by the aircraft, the first pilot feedbackindicating that it is safe to deploy the landing gear 20. In someembodiments, the first portion 202 starts at the start point 202 of thedetermined time period and/or distance range. The controller 100 isconfigured to issue a second pilot feedback when the second portion 204of the determined time period and/or distance range 200 is entered bythe aircraft (i.e., at point 230 as shown in the example of FIG. 2 ),the second pilot feedback indicating that the landing gear 20 can belowered in the efficient landing mode. In some embodiments, the secondportion 204 starts at the time and/or distance that the first portion202 ends. In some embodiments, the start point 230 of the second portion204 may be determined based on the topography below the flight path 50of the aircraft during the aircraft landing procedure. For example, thesecond portion 204 may start after the aircraft has passed over an urbanarea.

The controller 100 is configured to initiate landing gear deploymentwhen the aircraft is in the determined time period and/or distance range200, in response to receiving a deployment signal from the pilot.

In some embodiments, the controller 100 is configured to issue a pilotwarning if the aircraft passes a threshold time or threshold distance220 before the controller 100 receives the deployment signal from thepilot. The pilot warning indicates that landing gear deployment isrequired urgently. The threshold time or distance 220 is within thedetermined time period and/or distance range 200 and closer to aircraftlanding than the second portion 204. As shown in FIG. 2 , the thresholdtime or distance 220 is at the end point of the second portion 204. Inother embodiments, the threshold time or distance 220 may be between theend point of the second portion 204 and the end point 210 of thedetermined time period and/or distance range 200. The threshold time ordistance 220 may be based, for example, on a typical response time of apilot to the pilot warning. Such a feature may help to remind a pilotthat the landing gear 20 must be urgently deployed for safe aircraftlanding.

In some embodiments, the controller 100 may be configured to issue athird pilot feedback in the event that the aircraft exits the determinedtime period and/or distance range 200 before the controller receives thedeployment signal from the pilot. That is, if the aircraft passes theend point 220 of the determined time period and/or distance range 200without the deployment signal having been received by the controller100, the third pilot feedback is issued by the controller 100. The thirdpilot feedback indicates that initiating landing gear deployment hasbeen performed automatically by the controller 100. Such a feature mayhelp to ensure that a landing gear 20 is deployed at a safe time ordistance before aircraft landing even if the pilot has not commandedlanding gear deployment.

In some embodiments, the controller 100 may be operable in a first modein which initiation of landing gear deployment is delayed if thedeployment signal is received earlier than it is necessary to initiatelanding gear deployment, and a second mode in which initiation oflanding gear deployment is performed immediately upon receipt of thedeployment signal irrespective of the position of the aircraft relativeto the aircraft landing site 40. In some embodiments, for example if thecontroller 100 is in the first mode, the controller 100 may prevent thepilot from inputting the deployment signal until the aircraft enters thedetermined time period and/or distance range 200, or the second portion204 if in the efficient landing mode. For example, a landing geardeployment lever in the aircraft cockpit may only be movable to adeployment position after the aircraft has entered the determined timeperiod and/or distance range 200. In such embodiments, the first pilotfeedback may indicate that the pilot can command landing geardeployment.

In some embodiments, the controller 100 may be configured to delayinitiation of landing gear deployment until the aircraft enters thedetermined time period and/or distance range 200, in the event that thedeployment signal is received before the aircraft enters the determinedtime period and/or distance range 200. In such an embodiment, the firstpilot feedback may indicate that landing gear deployment has beeninitiated at the start point 208 of the determined time period and/ordistance range 200, the aircraft passing the start point 208 after thedeployment signal is received. If the controller 100 is configured toinitiate landing gear deployment in the efficient landing mode, thecontroller 100 may delay initiation of landing gear deployment until theaircraft enters the second portion 204 of the determined time periodand/or distance range 200, in the event that the deployment signal isreceived before the aircraft enters the second portion 204. In such anembodiment, the second pilot feedback may indicate that landing geardeployment has been initiated at a start point 230 of the second portion204 of the determined time period and/or distance range 200, theaircraft entering the second portion 204 after the deployment signal isreceived. Such features may help to increase the efficiency of theaircraft landing procedure by ensuring that the landing gear 20 is notdeployed earlier than necessary, even if the pilot has already commandedlanding gear deployment.

Operation of controllers 100 according to the invention will now bedescribed with reference to FIGS. 2 to 7 . FIGS. 3 to 7 are flowdiagrams depicting methods according to the present invention, and whichmay, at least in part, be employed by a controller 100 according to theinvention.

A controller 100 may be configured to perform a method 300 according toan embodiment of the invention. The controller 100 may be the controller100 described with reference to FIG. 2 . The method 300 is for deployinga landing gear at a determined aircraft position and is shown as a flowdiagram in FIG. 3 . The method 300 comprises: receiving an aircraftlanding gear deployment signal (block 310), receiving an aircraftposition signal indicative of a distance of the aircraft from anaircraft landing site 40 (block 320), receiving one or more flightsignals indicating one or more dynamic conditions or parameters (block330) relating to the flight of the aircraft, determining, based at leaston the one or more flight signals, a first aircraft position, relativeto the aircraft landing site 40, at which the landing gear deploymentshould commence (block 340) and deploying the landing gear (a) when theaircraft reaches the first aircraft position, in the event that thedeployment signal is received before the aircraft reaches the firstaircraft position, or (b) immediately, in the event that the deploymentsignal is received when the aircraft has passed the first aircraftposition (block 350).

In some embodiments, the controller 100 is configured to receive anaircraft landing gear deployment signal (block 310). The landing geardeployment signal may be generated in response to an input or action bythe aircraft pilot. Alternatively, the landing gear deployment signalmay be automatically generated by another aircraft system in response toa determination that certain criteria have been met. For example, thelanding gear deployment signal may be generated in response to theaircraft descending below a threshold altitude and/or decelerating tobelow a threshold speed.

The controller 100 is configured to receive an aircraft position signalindicative of a distance of the aircraft from an aircraft landing site40 (block 320). The aircraft position signal may be received from anaircraft GPS system. Alternatively, the aircraft position signal may begenerated in response to a determination of the aircraft position byanother aircraft system. The controller 100 may receive the aircraftposition signal at frequent intervals as the aircraft approaches theaircraft landing site 40.

The controller 100 is configured to receive one or more flight signalsindicating respective one or more dynamic conditions or parameters(block 330) relating to the flight of the aircraft. The one or moreflight signals may be received from other aircraft systems configured tomeasure parameters of the aircraft and/or the environmental conditionssurrounding the aircraft.

The controller 100 is configured to determine, based at least on thereceived one or more flight signals, a first aircraft position 230 (seeFIG. 2 ), relative to the aircraft landing site 40, at which the landinggear 20 should be deployed (block 340). In some embodiments, the firstaircraft position 230 represents a position at which landing geardeployment should be initiated so that the aircraft landing is conductedin an efficient landing mode. In some embodiments, in which thecontroller 100 comprises a memory 110, the controller 100 may beconfigured to determine the first aircraft position 230 based onaircraft landing site information stored in the memory 110.

The stored aircraft landing site information may include informationrelating to one or more of: the ground topography under the flight path50 of the aircraft as it approaches the aircraft landing site 40, therelative difficulty of the approach to the aircraft landing site 40,noise restrictions in place at the aircraft landing site 40, the lengthof the runway at the aircraft landing site 40 and the condition of thesurface of the runway. Information related to the ground topography mayinclude information on the location and size of urban areas under theflight path 50. The relative difficulty of the approach may includeinformation such as the height of buildings or other structures under ornear the flight path 50, for example some airports require that aircraftfly close to tall buildings or mountains, which may affect when alanding gear 20 should be deployed. Other information used indetermining the first aircraft position 230 may include the time of day;at some airports, noise restrictions are more restrictive later in theevening, so it may be beneficial to delay landing gear deployment untilthe aircraft is within a certain boundary around the aircraft landingsite 40.

The controller 100 is configured to, based on the deployment signal andthe aircraft position signal, trigger landing gear deployment (a) in theevent that the deployment signal is received before the aircraft reachesthe first aircraft position 230, when the aircraft reaches the firstaircraft position 230 or (b) immediately, in the event that thedeployment signal is received when the aircraft has passed the firstaircraft position 230 (block 360). In this way, the controller 100 isconfigured to delay landing gear deployment if the aircraft landing geardeployment signal is received earlier than the landing gear 20 needs tobe deployed, thus helping to increase the efficiency of the aircraftlanding procedure. The controller 100 may therefore be configured tomodify pilot behaviour to delay landing gear deployment until closer tothe latest point at which landing gear deployment can be initiatedcomparted to when a pilot would typically command landing geardeployment.

In some embodiments, the controller 100 (as described with reference toFIG. 2 and/or FIG. 3 ) may be configured to dynamically determine thefirst aircraft position 230 based on changes to the received one or moreflight signals over time. For example, as the aircraft approaches theaircraft landing site 40 the environmental conditions may change (forexample, the wind speed my change), which may influence the calculationof the determined first aircraft position 230. Alternatively, theaircraft may decelerate or descend faster or slower than predicted,which may influence the calculation of the determined first aircraftposition 230.

In some embodiments, the controller 100 (as described with reference toFIG. 2 and/or FIG. 3 ) may be configured to determine a second aircraftposition 210 (as shown in FIG. 2 ), relative to the aircraft landingsite 40, which indicates the closest aircraft position to the aircraftlanding site 40 at which the landing gear 20 can be deployed for a safelanding (block 360 of FIG. 4 ). The second aircraft position 210 iscloser to the aircraft landing site 40 than the first aircraft position230. In the event that the aircraft reaches the second position 210before the deployment signal has been received, the controller 100 mayas a precaution be configured to automatically trigger landing geardeployment (block 370 of FIG. 4 ). In some embodiments, the controller100 may trigger a warning as the aircraft approaches the second aircraftposition 210 to warn the pilot that the landing gear 20 should urgentlybe deployed. The controller 100 thus acts to determine a latest point210 before landing by which initiation of landing gear deployment shouldoccur and to either facilitate automatic deployment at that point, or towarn the pilot that he/she should urgently command landing geardeployment before the determined latest point 210.

In this way, the controller 100 can help to ensure that the landing gear20 is safely deployed before aircraft landing even if no deploymentsignal is received. In summary, the controller 100 is configured totrigger landing gear deployment at the first aircraft position 230 ifthe deployment signal has been received, to trigger landing geardeployment immediately upon receipt of the deployment signal if thedeployment signal is received when the aircraft is between the first andsecond aircraft positions 230, 210, or to trigger landing geardeployment when the aircraft reaches the second aircraft position 210and the deployment signal has not been received.

In some such embodiments, wherein the one or more flight signalscomprises an aircraft speed signal, the controller 100 is configured todetermine the second aircraft position 210 based at least on aircraftspeed and a landing gear deployment time (block 365 of FIG. 4 ). Thecontroller 100 may determine the second aircraft position 210 based onone or more other factors, which may comprise: a time required to checkthe status of the landing gear deployment, a safety factor time to allowa go-around in the event that an issue is detected which prevents a safelanding, or a time required for a landing gear shock absorber toequalise after landing gear deployment and before aircraft landing.

In some such embodiments, the controller 100 is configured such that, inthe event that the aircraft reaches the second aircraft position 210before the deployment signal has been received, to trigger acceleratedlanding gear deployment. That is, the controller 100 may cause thelanding gear extension and retraction system 30 to deploy the landinggear 20 in an accelerated mode so that the landing gear deployment timeis reduced. For example, in the accelerated mode, the landing gearextension and retraction system 30 may cause the landing gear 20 to movefrom the retracted position to the extended position at the same time ascausing the landing gear doors to move from the closed position to theopen position.

In some embodiments, the controller 100 (as described with reference toFIG. 2 and/or FIG. 3 ) may be configured, in the event that thedeployment signal is received before the aircraft reaches the firstaircraft position 230, to trigger a pre-landing landing gear systemcheck before triggering landing gear deployment (block 380 of FIG. 5 ).Typically, the pre-landing landing gear system check is performed whenthe landing gear 20 is in the deployed position. However, performing thesystem check before landing gear deployment permits a later landing geardeployment because less time is needed after landing gear deployment andbefore aircraft landing.

In some embodiments, the controller 100 (as described with reference toFIG. 2 and/or FIG. 3 ) may be configured to receive a landing gearstatus signal indicative of a status of the landing gear 20 in thedeployed position (block 390 of FIG. 6 ) and to trigger an automaticgo-around if the landing gear status signal indicates a fault in thedeployment of the landing gear 20 (block 400 of FIG. 6 ). For example,the controller 100 may be configured to receive a landing gear downlocksignal which indicates whether the landing gear 20 is locked into theextended position and to trigger an automatic go-around if the landinggear 20 is not locked into the extended position within a predeterminedtime or distance before aircraft landing. For example, with reference toFIG. 2 , the controller 100 may initiate an automatic go-around if thelanding gear 20 has not successfully deployed before the threshold timeand/or distance 215 before aircraft landing.

In some embodiments, the controller 100 (as described with reference toFIG. 2 and/or FIG. 3 ) may be configured, in the event that the aircraftreaches the first aircraft position 230 before the deployment signal isreceived, to trigger an aircraft system to issue a deployment warning tothe aircraft pilot (block 410 of FIG. 7 ). In this way, the pilot may bereminded to provide an input to generate the deployment signal.

In some embodiments, the controller 100 (as described with reference toFIG. 2 and/or FIG. 3 ) may be operable in a first mode, as describedwith reference to FIGS. 2 to 7 , and a second mode, in which, in theevent that the deployment signal is received before the aircraft reachesthe first aircraft position 230, the controller triggers landing geardeployment immediately upon receipt of the landing gear deploymentsignal. For example, in the second mode, the controller 100 triggerslanding gear deployment at the time that the pilot provides an input togenerate the deployment signal, even though the aircraft has not reachedthe first aircraft position 230. In some embodiments, the pilot mayselect the operating mode of the controller 100. The pilot may selectbetween the first and second modes based on, for example, the aircraftlanding site 40, the pilot's experience, the weather conditions or thecondition of the aircraft. For example, if there is a known fault withthe aircraft, the pilot may select the second mode so that the pilot hasgreater control over landing gear deployment.

Embodiments of the present invention comprise the method 300, as shownin FIG. 3 . In some embodiments, the method 300 comprises determiningthe first aircraft position and using that determined position toselectively deploy the landing gear 20 based on the relative position ofthe aircraft compared to the determined position. The method 300 mayoptionally comprise dynamically determining the first aircraft position230 based on changes to the received one or more flight signals overtime (block 345 of FIG. 3 ), such that the determined position maychange over the course of the aircraft landing procedure based on themost up-to-date information relating to the prevailing conditionsavailable to the controller 100. The method 300 may comprise one or moreof the methods shown as flow diagrams in FIGS. 4 to 7 , as describedabove with reference to the controller 100.

In some embodiments of the present invention, the one or more flightsignals indicate dynamic parameters of the aircraft, some examples ofwhich have been aforementioned. By way of further example, the one ormore flight signals may comprise signals indicating one or more of:aircraft speed, aircraft altitude, aircraft weight, aircraft flapposition and direction of landing. In some embodiments, the one or moreflight signals indicate atmospheric conditions at or near the aircraftlanding site 40. For example, the one or more flight signals maycomprise signals indicating one or more of: wind speed and direction,temperature, moisture on the runway, weather conditions.

FIG. 8 shows a schematic front view of an aircraft 500 according toembodiments of the present invention. In this embodiment, the aircraft500 comprises two main landing gears 510 and a nose landing gear 520. Insome embodiments, each landing gear 510, 520 is associated with acorresponding landing gear extension and retraction system (not shown)according to the present invention. In some embodiments, the aircraft500 comprises one or more controllers (not shown) according to thepresent invention. The aircraft 500 may comprise one controller 100 perlanding gear 510, 520. The aircraft 500 may comprise a common controller100 for the landing gears 510, 520.

It is to be noted that the term “or” as used herein is to be interpretedto mean “and/or”, unless expressly stated otherwise.

The above embodiments are to be understood as non-limiting illustrativeexamples of how the present invention, and aspects of the presentinvention, may be implemented. Further examples of the present inventionare envisaged. It is to be understood that any feature described inrelation to any one embodiment may be used alone, or in combination withother features described, and may also be used in combination with oneor more features of any other of the embodiments, or any combination ofany other of the embodiments. Furthermore, equivalents and modificationsnot described above may also be employed without departing from thescope of the present invention, which is defined in the accompanyingclaims.

The invention claimed is:
 1. An aircraft controller configured to: determine a time period and/or distance range over which deployment of a landing gear can be initiated for aircraft landing of an aircraft at an aircraft landing site, wherein the determining of the time period and/or the distance range is based on prevailing conditions during the aircraft landing and information related to the aircraft and the aircraft landing site, and wherein the determined time period and/or distance range comprises a determined first portion of the time period and/or the distance range, during which landing gear deployment can be safely initiated, and a determined second portion of the time period and/or the distance range, closer to aircraft landing than the first portion, during which the landing gear deployment can be safely initiated in an efficient landing mode; issue a first pilot feedback, before deployment of the landing gear and when the first portion of the determined time period and/or distance range is entered by the aircraft, the first pilot feedback indicating that deployment of the landing gear is safe; issue a second pilot feedback, before deployment of the landing gear and when the second portion of the determined time period and/or distance range is entered by the aircraft, the second pilot feedback indicating that the landing gear can be lowered in the efficient landing mode; and initiate landing gear deployment when the aircraft is in the determined time period and/or distance range, in response to receiving a deployment signal from a pilot of the aircraft.
 2. The aircraft controller according to claim 1, configured to issue a pilot warning if the aircraft passes a threshold time or threshold distance before the controller receives the deployment signal from the pilot, wherein the threshold time or distance is within the determined time period and/or distance range and closer to aircraft landing than the second portion, and wherein the pilot warning indicates that landing gear deployment is required urgently.
 3. The aircraft controller according to claim 1, configured to issue a third pilot feedback in the event that the aircraft exits the determined time period and/or distance range before the controller receives the deployment signal from the pilot, the third pilot feedback indicating that initiating landing gear deployment is being or has been performed automatically by the controller.
 4. The aircraft controller according to claim 1, further configured to delay the initiation of landing gear deployment until the aircraft enters the determined time period and/or distance range, in the event that the deployment signal is received before the aircraft enters the determined time period or distance range.
 5. An aircraft controller configured to: determine a range of time and/or distance in which landing gear deployment is appropriate for landing an aircraft at an aircraft landing site, wherein the determination of the range is based on prevailing flight conditions, performance of the aircraft and the aircraft landing site, and wherein the determination of the range includes determining a first portion of the range during which the landing gear deployment can be safely initiated, and determining a second portion of the range, closer to aircraft landing than the first portion, during which the landing gear deployment can be safely initiated in an efficient landing mode; issue a first pilot feedback, before the landing gear is deployed and while the aircraft is in the first portion, the first pilot feedback indicating that deployment of the landing gear is appropriate; issue a second pilot feedback before the landing gear is deployed and while the aircraft is in the second portion, the second pilot feedback indicating that the landing gear can be lowered in the efficient landing mode; and initiate landing gear deployment when the aircraft is in the range in response to receiving a deployment signal from a pilot of the aircraft.
 6. The aircraft controller according to claim 5, further configured to issue a pilot warning if the aircraft passes a threshold time or threshold distance before the controller receives the deployment signal from the pilot, wherein the threshold time or distance is within the range and closer to aircraft landing than the second portion, and wherein the pilot warning indicates that landing gear deployment is required urgently.
 7. The aircraft controller according to claim 5, further configured to issue a third pilot feedback in response to the aircraft exiting the range while approaching the landing site and before the controller receives the deployment signal from the pilot, the third pilot feedback indicating that initiating landing gear deployment is being or has been performed automatically by the controller.
 8. The aircraft controller according to claim 5, further configured to delay the initiation of landing gear deployment until the aircraft enters the range, if the deployment signal is received before aircraft enters the range.
 9. The aircraft controller according to claim 8, further configured to automatically initiate the landing gear deployment in response to the deployment signal and the aircraft entering the range, wherein the automatic initiation of the landing gear deployment is after the delay of the initiation of the landing gear deployment.
 10. A method performed by an aircraft controller comprising: determine a period and/or distance range over which deployment of a landing gear is appropriate for aircraft landing of an aircraft at an aircraft landing site, wherein the determining is based on prevailing conditions during the aircraft landing and information related to the aircraft and the aircraft landing site, and wherein the determining includes: determining a first portion of the period and/or of the distance range during which landing gear deployment can be safely initiated, and determining a second portion of the period and/or of the distance range, closer to the aircraft landing than the first portion, during which the landing gear deployment can be safely initiated in an efficient landing mode; issue a first pilot feedback, before deployment of the landing gear and when the first portion of the determined period and/or distance range is entered by the aircraft, the first pilot feedback indicating that deployment of the landing gear is safe; issue a second pilot feedback, before deployment of the landing gear and when the second portion of the determined period and/or distance range is entered by the aircraft, the second pilot feedback indicating that the landing gear can be lowered in the efficient landing mode; and initiate landing gear deployment when the aircraft is in the determined period and/or distance range.
 11. The method of claim 10, wherein the step of initiating the landing gear deployment is made in response to receiving by the controller a deployment signal from a pilot of the aircraft.
 12. The method according to claim 11, further comprising issuing a pilot warning indicating landing gear deployment is required urgently if the aircraft passes a second threshold time or a second threshold distance before the controller receives the deployment signal from the pilot, wherein the second threshold time or distance is within the determined period and/or distance range and is closer to aircraft landing than the second portion.
 13. The method according to claim 11, further comprising: issuing by the controller a third pilot feedback in response to the aircraft exiting the determined period and/or distance range before the controller receives a deployment signal from the pilot, wherein the third pilot feedback indicates that the landing gear deployment is being or has been performed automatically by the controller.
 14. The method according to claim 11, further comprising: delaying initiation of landing gear deployment until the aircraft enters the determined period and/or distance range, if the deployment signal is received before the aircraft enters the determined period or distance range.
 15. The method according to claim 14, further comprising automatically initiating the landing gear deployment in response to the deployment signal and the aircraft entering the determined period and/or distance range, wherein the automatic initiation of the landing gear deployment is after the delayed initiation of the landing gear.
 16. The method according to claim 10, wherein the issuance of the second pilot feedback occurs after the issuance of the first pilot feedback. 